This invention relates to the field of digital processing devices and, in particular, to a compact digital processing devices having a foldable keyboard.
Personal Digital Assistants (PDAs) have succeeded as useful devices as electronic replacements of calendars and address books. Unlike notebook computers, PDAs are small enough to hold in the palm of one hand (grasped entirely within the fingers of one hand) or fit in a pocket. They power on instantly, and are easy to use. They have touch screens and styluses, which when used with appropriate handwriting recognition or onscreen xe2x80x9cvirtualxe2x80x9d keyboards, allow for navigation, retrieving information, or entering small amounts of text. Recent advances in processing power, memory capacity, and application software, combined with the proliferation of wireless networks, have allowed PDAs to become very useful as communication devices and replacements for notebook computers. But in order to perform adequately as an e-mail machine or a notetaking device, a PDA must allow the user to quickly and comfortably enter text. Notebook computers have full size keyboards, which have been found to be the only successful solution for fast and convenient text entry. What is needed is a device that has the convenience of a PDA but has the text entry capabilities of the best notebook computers. What is also needed is a device that converts from a PDA to a notebook computer form factor.
The keyboard standard described by ISO 9241-4:1998(E) 6.2.1 calls for center-to-center key spacing of 19 mm+/xe2x88x921 mm. ISO 9241-4:1998(E) 6.2.3 calls for preferred key displacement between 2.0 mm and 4.0 mm. Experience has shown that keyboards should be designed in conformance with these standards in order to allow touch-typing.
U.S. Pat. No. 5,949,408, assigned to Hewlett-Packard Company, describes a product marketed by Hewlett-Packard known as the xe2x80x9cOmniGo 100xe2x80x9d and is shown in FIG. 1A. It is a PDA with a built-in keyboard. However, in order to fit the keyboard in a housing small enough for a PDA size, the keyboard is a small xe2x80x9cchickletxe2x80x9d type that does not allow touch-typing. The center-to-center spacing of the keys is less than 13 mm horizontally and less than 10 mm vertically. The key xe2x80x9ctravelxe2x80x9d or displacement is less than 0.5 mm. This is clearly outside the ISO specification quoted above.
GB 2,279,617 describes a PDA, shown in FIG. 1C, with a built-in keyboard. However, the keyboard is a xe2x80x9cflexible filmxe2x80x9d or membrane type keyboard. Keyboards like this have key displacements of a fraction of a millimeter and lack tactile feedback. For this reason they prevent touch-typing. Additionally, a keyboard of this design would require placement on a rigid flat surface and could not be use on one""s lap without the addition of such a surface.
EP 691,603 describes a notebook computer with a built-in folding keyboard. However, this device does not convert to a hand held PDA.
U.S. Pat. No. 5,666,694 describes a double hinge arrangement for a xe2x80x9cclam-shellxe2x80x9d like device shown in FIG. 1B. It uses a friction clutch and spring mechanism to sequence the rotation of the two panels. However, this mechanism is complicated, consumes much space, and the relative positions of the two panels are not necessarily kept constant.
Some prior art PDAs employ screen rotation techniques to rotate the configuration of the screen from portrait to landscape mode when the PDA is switched from a PDA data entry mode to a keyboard data entry mode. Various methods have been used to perform such screen rotation. For examples, using software pixel manipulation (e.g., as used in the HandEra, and Jimmy Software for the Compaq iPAQ) and by hardware assisted pixel manipulation (e.g., as performed by the MediaQ chip in Sony""s Clie).
Another screen rotation method used in Hewlett Packard""s OmniGo employs a customized LCD panel where the rotation is performed in the LCD panel, itself, in order to provide minimum impact on the software. One disadvantage of the screen rotation techniques employed in the Hewlett Packard OmniGo is that the LCD panel must be symmetrical (e.g., 240 v 240), thereby limiting the size of the display screen that may be used in PDAs. Another disadvantage of the screen rotation techniques employed in the Hewlett Packard OmniGo is that such techniques may only be used with monochrome displays that contain only a single cell for each pixel. For a color screen, each of the pixels, for example, may contain three colorsxe2x80x94red, green, and bluexe2x80x94(RGB) cells lined in one direction, which require realignment to prevent color split. Such realignment may not be possible with the screen rotation techniques employed in the Hewlett Packard OmniGo. Another disadvantage of the Hewlett Packard OmniGo is that the device may not be practical for rotation beyond 90 degrees (e.g., 270 degrees of rotation), thereby limiting its range of use.
The present invention pertains to a digital processing device having a foldable keyboard. In one embodiment, the digital process device includes a rigid base, a display assembly with a display screen, a foldable keyboard assembly coupled with the base, and a hinge assembly that couples the display assembly to the base. The hinge assembly allows the display assembly to rotate between a first configuration and a second configuration.
Additional features and advantages of the present invention will be apparent from the accompanying drawings, and from the detailed description that follows below.